Formation of struvite urinary stones and approaches towards the inhibition-A review

Background: Struvite is one of the most common urinary/ kidney stones, composed of magnesium ammonium phosphate (MgNHPO4 center dot H2O). They are also termed as infection stones as these are associated with urinary tract infections. Numerous studies have been carried out to examine the growth and inhibition of struvite stones. Objective: This review summarizes various reports on the factors responsible for inducing struvite stones in the kidney and gives a detailed account of studies on inhibition of growth of struvite crystals. Results: The presence of urea-splitting bacteria such as Proteus mirabilis and alkaline pH plays a crucial role in struvite formation. In vitro inhibition of struvite stones by various chemical agents were examined mainly in artificial urine whereas inhibition by herbal extracts was studied in vitro by gel diffusion technique. Herbal extracts of curcumin, Boerhaavia diffusa Linn, Rotula aquatica and many other plants, as well as some chemicals like pyrophosphate, acetohydroxamic acid, disodium EDTA and trisodium citrate, were reported to successfully inhibit struvite formation. Conclusion: The present review recapitulates various factors affecting the growth of struvite urinary stones and the inhibitory role of certain chemicals and herbal extracts. Most of the tested plants are edible hence can be easily consumed without any adverse effects whereas the side effects of chemicals are unknown due to lack of toxicity studies. Thus, the use of herbal extracts might serve as an alternate and safe therapy for prevention of struvite stones.